Pulse generator

ABSTRACT

A control circuit for providing a voltage pulse of a variable height and width upon the occurrence of a predetermined condition includes, a pair of input terminals, a pair of output terminals, first switch means connected to the input terminals and being nonconductive upon the occurrence of the predetermined event, second switch means responsive to the first switch means and having a conductive condition when the first switch means is nonconductive and third switch means having a conductive condition when the second switch means is conductive establishing a pulse on the output terminals. Means are provided for controlling the width of the output pulse by controlling the period of conduction of the second switch means and means connected to the output of the third switch means are provided for controlling the height of the pulse.

United States Patent Haurykiewicz [s4] PULSE GENERATOR [72] Inventor: John M. Haurykiewicz, Kenosha,

Wis.

[73] Assignee: Eaton Corporation, Cleveland, Ohio 22] Filed: July 1,l971

21 Appl.No.: 158,921

Primary Examiner-James W. Lawrence Martin et al ..307/266 [151 3,705,314 [4 Dec. 5, 1972 Assistant Examiner-Harold A. Dixon Attorney-Leslie H. Blair et al;

[57] ABSTRACT A control circuit for providing a voltage pulse of a variable height and width upon the occurrence of a predetermined condition includes, a pair of input terminals, a pair of output terminals, first switch means connected to the input terminals and being nonconductive upon the occurrence of the predetermined event, second switch means responsive to the first switch means and having a conductive condition when the first switch means is nonconductive and third switch means having a conductive condition when the second switch means is conductive establishing a pulse on'the output terminals. Means are provided for controlling the width of the output pulse by controlling the period of conduction of the second switch means and means connected to the output of the third switch means are provided for controlling the height of the pulse.

9 Claims, 3 Drawing Figures PULSEGENERATOR The present invention relates to a control circuit for producing an output pulse and more particularly to a control circuit for providing a pulse having a variable width and height.

Known control circuits for producing voltage pulses generally do not incorporate means for separately controlling the height and width of the pulse. This is extremely important if the area of the pulse represents a predetermined amount of energy to be applied to a system since the shape of the pulse determines not only the energy but the speed at which the energy is applied, i.e., pulses of equal area may have varying widths. Moreover, in most known control circuits for providing a pulse, accurate override means for stopping the pulse are not provided due to the fact that elements of the control must discharge over a time period once a command to stop the pulse is received.

Accordingly, an object of the present invention is to provide a new andimproved control circuit for providing a voltage pulse of a separately variable width and height which overcomes the hereinabove discussed disadvantages and which is economical, reliable and includes positive override protection for immediately stopping the pulse upon initiation of a command to stop the pulse. a

Another object of the present invention is to provide a new and improved control circuit for providing a voltage pulse of a variable width and height, the area of which represents a predetermined amount of energy to be applied to a system upon the occurrence of a predetermined event including, a pair of input and output terminals, first switch means connected to the input terminals and responsive to the predetermined event, means connected to the input terminals for controlling the width of the pulse, second switch means responsive to the first switch means having a conductive condition providing a pulse on the output terminals and means for controlling the height of the pulse connected to the second switch means. a a

A further object of the present invention is to provide a new and improved control circuit for providing a voltage pulse of a variablewidth and height upon the occurrence of a predetermined event including a pair of input and output terminals, first switch means associated with the input terminals having a nonconductive condition upon the occurrence of a predetermined event, second switch means having a nonconductive condition and a conductive condition when the first switch means is nonconductive, third switch means having a conductive condition and a nonconductive condition when the output pulse is established on the output terminals, fourth switch means having a nonconductive condition and a conductive condition establishing the pulse on the output terminals, means for controlling the width of the pulse connected to the second switch means and means connected to the fourth switch means for controlling the height of the F16. 2 is a graphical illustration off theoutput wherein the voltage pulse has a fast decay; and

FIG. 3 is a graphical illustration of the output wherein the voltage pulse has a slow decay and a capacitor is disposed between the output terminals.

The present invention relates to a control circuit for providing a voltage pulse upon the occurrence of a predetermined event which has a separately variable width and height. The control circuit includes a plurality of switching means, which are in the form of transistors, which cooperate to provide a pulse on the output terminal of the control circuit. Separate means are provided for adjusting the height and the width of the pulse.

The control circuit 10 as illustrated in FIG. 1, in cludes input terminals 11 and 14. Terminal 12 is adapted to have a positive voltage applied thereto which is directed along line 13 and the input terminal 14 is a ground terminal which holds the line 15 at a common potential. A pair of output terminals 16 and 18 are also provided, with the terminal 18 being connected to the input terminal14 by line 15 and held at the ground potential.

'A transistor '20, having a normally conductivecondition, has its base connected. to the input terminal 11 through a diode 24. The transistor 20 is normally biased to a conductive condition by a potential applied from the terminal 12 through the resistor 22 to the base of the transistor 20. A'diode 24 and a pair of normally opened contact 26 is series connected with the resistor 22 between the terminal 12 and the terminal 14. The contact 26 is preferably connected to an external'relay which is energized upon the occurrence'of a predetermined event to close contact 26. When'contact-26 is closed upon the occurrence of the predetermined event, the base of transistor 20 will be connected to the input terminal 14 via the closed contact 26. Thus,closing of the contact 26 will ground the base of transistor 20 to thereby render the transistor 20 nonconductive.

,Series connected between the terminal 12 and the collector of transistor 20 are resistors 28, 30, and 32 and a diode 34. Connectedbetween the emitter of the transistor 20 and the common terminal 14 is adiode 37. When the external contact 26 -is in an opened condition and the terminal 12 biases the base of transistor 20, circuit will be completed through the resistors 28, 30 and 32, diode 34, the collector emitter circuit of transistor 20, and diode 37 to the common line 15.

A transistor 36 is connected between the line 13 and the line 15. The transistor 36 has its base connected through a resistor 38 to the resistor 30. When transistor 20 is in a conductive condition, the base of transistor 36 will not have a biasing potential applied thereto through resistor 38. When the external contacts 26 are closed and transistor 20 is rendered nonconductive. a biasing potential will be applied via the resistor 38 to the base of transistor 36 to thereby render transistor 36 conductive. Simultaneously with the conduction of transistor 36, a capacitor 40, which is series connected with resistors 28 and 30 between lines 13 and 15, will start charging. The charging of capacitor 40 will control the output voltage of the collector emitter circuit of transistor 36 so that the emitter voltage of transistor 36 will rise in an exponential manner as capacitor 40 charges up.

The output voltage of transistor 36 is applied through a diode 42 to the cathode of a Zener diode 44. Zener diode 44 has it anode connected to the base of a normally nonconductive transistor 46 which is connected between lines 13 and 15. When the emitter voltage of transistor 36 reaches the break-down point of Zener diode 44, the Zener diode will conduct and a potential will be applied to the base of a transistor 46 to bias transistor 46 to its conductive condition.

The transistor 46 has its emitter connected to the common line 15 and its collector connected to the base of a transistor 48 and to the positive line 13 via a resistor 50. The base of transistor 48 is connected through a diode 52 to the collector of transistor 20. When transistor is conductive, the base of transistor 48 will be grounded through the diode 52 and the collector emitter circuit of transistor 20 to thereby prevent conduction of transistor 48. When transistor 20 is rendered nonconductive by the closing of the external contact 26, a potential will be applied from line 13 through the resistor 50 to the base of transistor 48 to thereby render transistor 48 conductive. When transistor 46 is biased to its conductive condition by the breakdown of Zener diode 44 the base of transistor 48 will be grounded through the collector emitter circuit of transistor 46 and the transistor 48 will be rendered nonconductive.

A PNP transistor 54 has its collector emitter circuit connected between the line 13 and the common line 15. The base of transistor 54 is connected to the collector of transistor 48. When transistor 48 is conductive, the base of transistor 54 will have a potential applied thereto to render transistor 54 conductive. When transistor 48 is nonconductive, transistor 54 will also be nonconductive.

Connected to the collector of transistor 54 is a variable resistor 54 having a wiper arm 58 which is connected to the output terminal 16 through a diode 60. The transistor 54 acts as an amplifier and is operable to direct an output pulse upon conduction of transistors 48 through the wiper arm 58 of the variable resistor 56 to the output terminal 16. The magnitude of the height of the output pulse can be controlled by the variable resistor 56 by setting the wiper arm 58. It should be apparent that transistor 54, when conductive effects the establishment of the pulse between the output terminals 16 and 18. Transistor 54 is conductive only when transistor 48 is conductive and transistor 20 is nonconductive.

It should be apparent that transistor 20 is normally conductive and transistors 36, 46, 48, and 54 are normally nonconductive. When transistor 20 is rendered nonconductive by the closing of the external contacts 26, transistor 36 will be rendered conductive. Transistor 48 will also be rendered conductive due to the fact that the base is no longer grounded via the diode 52 through transistor 20. When transistor 48 is conductive, transistor 54 will conduct to effect the establishment of an output pulse between the output terminals 16 and 18. The conduction of transistor 36, due to the nonconduction of transistor 20, will apply a voltage potential to the Zener diode 44. The voltage potential will have an exponential function due to the charging of capacitor 40 via the variable resistor 28. When the capacitor 40 is charged to a predetermined value, the Zener diode 44 will break down and bias transistor 46 into conduction. Conduction of transistor 46 will render transistor 48 nonconductive thereby rendering transistor 54 nonconductive to terminate the output pulse applied between the terminals 16 and 18.

The width of the output pulse is controlled by the value of the variable resistor 28 and the capacitor 40. The resistor 28 and capacitor 40 form a RC timing circuit to control the charging of capacitor 40 and thereby control the period of time it takes for Zener diode 44 to break down and effect conduction of transistor 46 after transistor 20 is rendered non-conductive by the closing of contacts 26. The resistor 28 and capacitor 40 will operate to control the output voltage on transistor 36 so that the Zener diode 44 is broken down and transistor 46 starts to conduct after a predetermined period of time to terminate the output pulse. Thus, the width of the pulse, which is directly related to the period of time between which transistor 20 isrendered nonconductive and transistor 46 is rendered conductive, is controlled by the variable resistor 28 in cooperation with the capacitor 40. The height of the pulse can be set by the variable resistor 56. Thus, pulses of various configurations can be directed to the output terminals 16 and 18 by setting the variable resistors 28 and 56 of the present control circuitry.

FIGS. 2 and 3 illustrate the various configurations that the output pulse may take. In FIG. 2 the pulse has an output width designated as X which is controlled by the setting of the variable resistor 28 and an output height Y which is controlled by the setting of the variable resistor 56. [fit is desired, the pulse may be made to decay rather than stop abruptly as is illustrated in FIG. 2. A slow decay of the pulse maybe initiated, as is illustrated in FIG. 3, by the addition of a capacitor 63 illustrated connected by dotted lines between the common line 15 and the output terminal 16. In this case the exponential decay of the pulse can be controlled by the value of the capacitor 63.

It should be appreciated that closing of the external contact 26 immediately effect conduction of transistors 48 and 54 to establish an output between the output terminals 16 and 18. Moreover, if the external contact 26 is opened while the output pulse is being applied to the output terminals, the opening of contact 26 will immediately render transistors 48 and 54 nonconductive by grounding the base of transistor 48 through the diode 52 to terminate the pulse applied to the output terminals. Thus, a precise control has been provided in that the contact 26 acts to override the control circuitry in the event that the contact 26 is opened before the pulse has been terminated on the output terminals to thereby terminate the pulse prematurely.

While the present control circuit is utilizable for many applications a preferred use thereof is to apply to a system a pulse having an area indicative of a predetermined amount of energy that the system must generate. For example, the present control circuit can be used with a system for controlling a press drive wherein the control circuit 10 is utilized to provide an output pulse having a magnitude which represents the amount of energy required by the press drive to overcome the static friction of the fly wheel thereof. In this type of embodiment, the control circuit 10 will be operable to apply a pulse having an area which is indicative of the energy neededto start the system into operation and overcome the static friction of the press drive, A control system for such a press drive which may be used in conjunction with the present circuitry is disclosed in the OCallahan application Ser. No. 83,826 filed Oct. 26, 1970.

From the foregoing it should be apparent that a new and improved control circuit has been provided for providing a voltage pulse of a variable width-and height upon the occurrence'of a predetermined condition. The control circuit includes a first switch means responsive to theoccurrence of apredetermined event, second switch means responsive to the first switch means and third switch means connected to the second switch means for establishing a pulse on the output terminals, Means areprovided connected to the second switch means for controlling the height of the output pulseand means are connected to the output of the third switch means for controlling the width of the pulse. I

What I claim is:

l. A control circuit for providing a voltage pulse of a variable width and height during the occurrence of a predetermined event comprising a pair of input terminals, a pair of output terminals, first-switch means associated with said input terminals having a normally conductive condition prior to the occurrence of the predetermined event and a nonconductive condition only upon the occurrence and during the continuation of the predetermined event, second switch means having a nonconductive condition when said first switch means is conductive and activated to a conductive condition producing an output pulse on said output terminals in response to nonconduction of said first switch means, third switch means having a nonconductive condition when said first switch means is in said conductive condition and a conductive condition when said first switch means is in said nonconductive condition and the output pulse, is applied to said output terminals, fourth switch means having a nonconductive condition and a conductive condition for terminating the output pulse on said output terminals during the nonconduction of said first switch means, meansfor controlling the width of said pulse connected to said third switch means for controlling the period of time between nonconduction of said first switch means and conduction of said fourth switch means in response to said first switch means being nonconductive, and means connected to said second switch means for controlling the magnitude of the pulse height that said second switch means directs to said output terminals.

2. A control circuit for providing a voltage pulse of a variable width and height upon the occurrence of a predetermined event as defined in claim 1 wherein said means for controlling the width of said pulse includes a resistor and a capacitor forming an RC timing circuit connected to said third switch means, said second switch means having a conductive condition when said first and fourth switch means are nonconductive, said fourth switching means having a conductive condition when said third switch means applies a predetermined potential to said fourth switch means, said resistor and capacitor controlling the voltage that said third switch means applies to said fourth switch means to provide a time delay between nonconduction of said first switch means and conduction of said fourth switch means by controlling the potential that said third switch means applies to said fourth switch means. I

3. A control circuit for providing a voltage pulse of a variable width and height upon the occurrence of a predetermined event as defined in claim 2 wherein the voltage that said second switch means applies to said fourth switch means has a magnitude which increases as an exponential function and which is controlled by said resistor and capacitor.- v

4. A control circuit for providing a voltage pulse of a variable width and height upon theocc'urrenceof a predetermined eventas defined in claim 2 wherein said means for controlling the magnitude of the pulse height includes a resistor connected tosaid second switch means.

5. A control circuit for providing a voltage pulse of a variable width and height upon the occurrence of a predetermined event comprising a pair of input terminals, a pair of output terminals, first switch means associated with said input terminals having a normally conductive condition and a nonconductive condition upon the occurrence of the predetermined event, third I switch means having a nonconductive condition when said first switch means is conductive and activated to a conductive conduction in response to nonconduction of said first switch means, fourth switch means having a conductive condition and a nonconductive condition when said first switch means is in said nonconductive condition and the output pulse'is applied to said output terminals, second switch means having a nonconductive condition and a conductive condition establishing a pulseon said output terminals in response to nonconduction of said first switch means, means for controlling the width of said pulse connected to said third switch means for controlling the period of time said fourth switch means is in said nonconductive condition in response to said first switch means being nonconduc tive, means connected to said second switch means for controlling the'magnitude-of the pulse height that said second switch means directs to said output terminals, said means for controlling the width of said pulse includes a resistor and a capacitor forming an RC timing circuit connected to said ,third switch means, said second switch means having a conductive condition when said first and third switch means are nonconductive, said fourth switching means having a conductive condition when said third switch means applies a predetermined potential to said fourth switch means, said resistor and capacitor controlling the voltage that said third switch means applies to said fourth switch means to provide a time delay between nonconduction of said first switch means and conduction of said fourth switch means by controlling the potential that said third switch means applies to said fourth switch means, said voltage that said third switch means applies to said fourth switch means has a magnitude which increases as an exponential function and which is controlled by said resistor and capacitor, said means for controlling the magnitude of the pulse height includes a resistor connected to said second switch means, said first switch means includes a third transistor, said third switch means includes a fourth transistor, said fourth switch means includes a fifth transistor and said second switch means includes a first transistor and a second transistor, said fourth transistor having its base connected to the collector of said third transistor and being nonconductive when said third transistor is conductive, said fifth transistor having its base operatively connected to the emitter of said fourth transistor and being conductive when said fourth transistor applies a predetermined potential to the base of said fifth transistor, said first transistor having its base operatively connected to the collector of said third transistor and to the collector of said fifth transistor and being nonconductive when said third transistor is conductive and being nonconductive when said fifth transistor is conductive, and said second transistor having its base connected to the collector of said first transistor and being conductive when said first transistor is conductive.

6 A control circuit for providing a voltage pulse of a variable width and height upon the occurrence of a predetermined event as defined in claim 17 further including a Zener diode connected between the emitter of said fourth transistor and the base of said fifth transistor, said Zener diode enabling said fourth transistor to apply a potential to the base of said fifth transistor when the potential is equal to the predetermined potential, and wherein said resistor and capacitor forming said RC timing circuit are connected to the base of said fourth transistor and control the potential that said fourth transistor applies to the base of fifth transistor.

7. A control circuit for providing a voltage pulse of a variable width and height upon the occurrence of a predetermined event as defined in claim further including a pair of normally opened contacts connected to the base of said first transistor for sensing the occurrence of the predetermined event, said contacts closing in response to the occurrence of the predetermined event to render said first transistor nonconductive and effect the establishment of the output pulse on said output terminals and wherein said contacts are operable when opened prior to conduction of said fifth transistor to terminate the output pulse on said output terminals by rendering said first transistor conductive.

8. A control circuit for providing a voltage pulse of a variable width and height upon the occurrence of a predetermined event comprising a pair of input terminals, a pair of output terminals, first switch means connected to said input terminals and responsive to the occurrence of the predetermined event for effecting a pulse on said output terminals, means connected to said input terminals for controlling the width of pulse on said output terminals, second switch means responsive to said first switch means connected to said output terminals and having a nonconductive condition and a conductive condition providing a pulse on said output terminals upon the occurrence of said predetermined event, means associated with said second switch means for controlling the height of said output pulse when said second switch means is in said conductive conduction, third switch means connected to said first switch means, said third switch means having a nonconductive condition when said first switch means is in said eonductive condition and a conductive condition when said first switch means is in said nonconductive condition, fourth switch means connected to said second switch means and said third switch means, said third switch means havin a conductive condition when said first switch means as a conductive condition, said fourth switch means applying a predetermined potential to said second switch means to render said second switch means nonconductive, said second switch means having a conductive condition to apply a pulse to said output terminals when said first switch means and said fourth switch means are nonconductive, said means for controlling the width of the pulse on said output terminals includes a resistor and a capacitor connected to said third switch means and cooperating to form an RC timing circuit for controlling the potential applied by said third switch means to said fourth switch means upon said first switch means reaching its nonconductive condition, said resistor and capacitor providing for a time delay between the nonconduction of said first switch means and the conduction of said fourth switch means by controlling the potential that said third switch means applies to said fourth switch means, said means associated with said second switch means for controlling the height of said output pulse includes a variable resistor connected between said second switch means and said output terminal for controlling the magnitude of the height of the pulse, said second switch means includes a first transistor and a second transistor, said first transistor being operatively connected to said first switch means and said fourth switch means, said second transistor having its base connected to said first transistor and its collector connected to said variable resistor, said first transistor having a conductive condition when said first switch means is in said nonconductive condition and said fourth switch means is in said nonconductive condition and said second transistor having a conductive condition when said first transistor is in said conductive condition, and wherein said first switch means includes a third transistor, said third switch means includes a fourth transistor, and said fourth switch means includes a fifth transistor, said third transistor having a conductive condition and a nonconductive condition in response to the occurrence of the predetermined event, said fourth transistor having its base operatively connected with the collector of said third transistor and its emitter operatively associated with the base of said fifth transistor, said fourth transistor having a conductive condition when said first transistor is nonconductive, said fifth transistor having its collector connected to the base of said first transistor and having a conductive condition when said fourth transistor applies a predetermined potential to the base of said fifth transistor.

9. A control circuit for providing a voltage pulse of a variable width and height as defined in claim 8 further including a Zener diode connected between the emitter of said fourth transistor and the base of said fifth transistor, said Zener diode having a conductive condition when said fourth transistor applies a pr-determined potential thereto, said resistor and capacitor forming said RC timing circuit controlling the potential applied by said fourth transistor to said Zener diode and the base of said fifth transistor to control the width of the pulse and the period of conduction of said first and second transistor. 

1. A control circuit for providing a voltage pulse of a variable wiDth and height during the occurrence of a predetermined event comprising a pair of input terminals, a pair of output terminals, first switch means associated with said input terminals having a normally conductive condition prior to the occurrence of the predetermined event and a nonconductive condition only upon the occurrence and during the continuation of the predetermined event, second switch means having a nonconductive condition when said first switch means is conductive and activated to a conductive condition producing an output pulse on said output terminals in response to nonconduction of said first switch means, third switch means having a nonconductive condition when said first switch means is in said conductive condition and a conductive condition when said first switch means is in said nonconductive condition and the output pulse is applied to said output terminals, fourth switch means having a nonconductive condition and a conductive condition for terminating the output pulse on said output terminals during the nonconduction of said first switch means, means for controlling the width of said pulse connected to said third switch means for controlling the period of time between nonconduction of said first switch means and conduction of said fourth switch means in response to said first switch means being nonconductive, and means connected to said second switch means for controlling the magnitude of the pulse height that said second switch means directs to said output terminals.
 2. A control circuit for providing a voltage pulse of a variable width and height upon the occurrence of a predetermined event as defined in claim 1 wherein said means for controlling the width of said pulse includes a resistor and a capacitor forming an RC timing circuit connected to said third switch means, said second switch means having a conductive condition when said first and fourth switch means are nonconductive, said fourth switching means having a conductive condition when said third switch means applies a predetermined potential to said fourth switch means, said resistor and capacitor controlling the voltage that said third switch means applies to said fourth switch means to provide a time delay between nonconduction of said first switch means and conduction of said fourth switch means by controlling the potential that said third switch means applies to said fourth switch means.
 3. A control circuit for providing a voltage pulse of a variable width and height upon the occurrence of a predetermined event as defined in claim 2 wherein the voltage that said second switch means applies to said fourth switch means has a magnitude which increases as an exponential function and which is controlled by said resistor and capacitor.
 4. A control circuit for providing a voltage pulse of a variable width and height upon the occurrence of a predetermined event as defined in claim 2 wherein said means for controlling the magnitude of the pulse height includes a resistor connected to said second switch means.
 5. A control circuit for providing a voltage pulse of a variable width and height upon the occurrence of a predetermined event comprising a pair of input terminals, a pair of output terminals, first switch means associated with said input terminals having a normally conductive condition and a nonconductive condition upon the occurrence of the predetermined event, third switch means having a nonconductive condition when said first switch means is conductive and activated to a conductive conduction in response to nonconduction of said first switch means, fourth switch means having a conductive condition and a nonconductive condition when said first switch means is in said nonconductive condition and the output pulse is applied to said output terminals, second switch means having a nonconductive condition and a conductive condition establishing a pulse on said output terminals in response to nonconduction of said first switch means, means for controlling the width of said pulse connecteD to said third switch means for controlling the period of time said fourth switch means is in said nonconductive condition in response to said first switch means being nonconductive, means connected to said second switch means for controlling the magnitude of the pulse height that said second switch means directs to said output terminals, said means for controlling the width of said pulse includes a resistor and a capacitor forming an RC timing circuit connected to said third switch means, said second switch means having a conductive condition when said first and third switch means are nonconductive, said fourth switching means having a conductive condition when said third switch means applies a predetermined potential to said fourth switch means, said resistor and capacitor controlling the voltage that said third switch means applies to said fourth switch means to provide a time delay between nonconduction of said first switch means and conduction of said fourth switch means by controlling the potential that said third switch means applies to said fourth switch means, said voltage that said third switch means applies to said fourth switch means has a magnitude which increases as an exponential function and which is controlled by said resistor and capacitor, said means for controlling the magnitude of the pulse height includes a resistor connected to said second switch means, said first switch means includes a third transistor, said third switch means includes a fourth transistor, said fourth switch means includes a fifth transistor and said second switch means includes a first transistor and a second transistor, said fourth transistor having its base connected to the collector of said third transistor and being nonconductive when said third transistor is conductive, said fifth transistor having its base operatively connected to the emitter of said fourth transistor and being conductive when said fourth transistor applies a predetermined potential to the base of said fifth transistor, said first transistor having its base operatively connected to the collector of said third transistor and to the collector of said fifth transistor and being nonconductive when said third transistor is conductive and being nonconductive when said fifth transistor is conductive, and said second transistor having its base connected to the collector of said first transistor and being conductive when said first transistor is conductive. 6 A control circuit for providing a voltage pulse of a variable width and height upon the occurrence of a predetermined event as defined in claim 17 further including a Zener diode connected between the emitter of said fourth transistor and the base of said fifth transistor, said Zener diode enabling said fourth transistor to apply a potential to the base of said fifth transistor when the potential is equal to the predetermined potential, and wherein said resistor and capacitor forming said RC timing circuit are connected to the base of said fourth transistor and control the potential that said fourth transistor applies to the base of fifth transistor.
 7. A control circuit for providing a voltage pulse of a variable width and height upon the occurrence of a predetermined event as defined in claim 5 further including a pair of normally opened contacts connected to the base of said first transistor for sensing the occurrence of the predetermined event, said contacts closing in response to the occurrence of the predetermined event to render said first transistor nonconductive and effect the establishment of the output pulse on said output terminals and wherein said contacts are operable when opened prior to conduction of said fifth transistor to terminate the output pulse on said output terminals by rendering said first transistor conductive.
 8. A control circuit for providing a voltage pulse of a variable width and height upon the occurrence of a predetermined event comprising a pair of input terminals, a pair of output terminals, first switch means Connected to said input terminals and responsive to the occurrence of the predetermined event for effecting a pulse on said output terminals, means connected to said input terminals for controlling the width of pulse on said output terminals, second switch means responsive to said first switch means connected to said output terminals and having a nonconductive condition and a conductive condition providing a pulse on said output terminals upon the occurrence of said predetermined event, means associated with said second switch means for controlling the height of said output pulse when said second switch means is in said conductive conduction, third switch means connected to said first switch means, said third switch means having a nonconductive condition when said first switch means is in said conductive condition and a conductive condition when said first switch means is in said nonconductive condition, fourth switch means connected to said second switch means and said third switch means, said third switch means having a conductive condition when said first switch means has a conductive condition, said fourth switch means applying a predetermined potential to said second switch means to render said second switch means nonconductive, said second switch means having a conductive condition to apply a pulse to said output terminals when said first switch means and said fourth switch means are nonconductive, said means for controlling the width of the pulse on said output terminals includes a resistor and a capacitor connected to said third switch means and cooperating to form an RC timing circuit for controlling the potential applied by said third switch means to said fourth switch means upon said first switch means reaching its nonconductive condition, said resistor and capacitor providing for a time delay between the nonconduction of said first switch means and the conduction of said fourth switch means by controlling the potential that said third switch means applies to said fourth switch means, said means associated with said second switch means for controlling the height of said output pulse includes a variable resistor connected between said second switch means and said output terminal for controlling the magnitude of the height of the pulse, said second switch means includes a first transistor and a second transistor, said first transistor being operatively connected to said first switch means and said fourth switch means, said second transistor having its base connected to said first transistor and its collector connected to said variable resistor, said first transistor having a conductive condition when said first switch means is in said nonconductive condition and said fourth switch means is in said nonconductive condition and said second transistor having a conductive condition when said first transistor is in said conductive condition, and wherein said first switch means includes a third transistor, said third switch means includes a fourth transistor, and said fourth switch means includes a fifth transistor, said third transistor having a conductive condition and a nonconductive condition in response to the occurrence of the predetermined event, said fourth transistor having its base operatively connected with the collector of said third transistor and its emitter operatively associated with the base of said fifth transistor, said fourth transistor having a conductive condition when said first transistor is nonconductive, said fifth transistor having its collector connected to the base of said first transistor and having a conductive condition when said fourth transistor applies a predetermined potential to the base of said fifth transistor.
 9. A control circuit for providing a voltage pulse of a variable width and height as defined in claim 8 further including a Zener diode connected between the emitter of said fourth transistor and the base of said fifth transistor, said Zener diode having a conductive condition when said fourth transistor applies a pr-determinEd potential thereto, said resistor and capacitor forming said RC timing circuit controlling the potential applied by said fourth transistor to said Zener diode and the base of said fifth transistor to control the width of the pulse and the period of conduction of said first and second transistor. 